MPLS Ping #
虽然是 Ping 的一种， 但是采用的不是 ICMP 探针检测中间路径，使用的是 IPv4 或者 IPv6 UDP 数据包。 有两种报文，MPLS Echo Request/MPLS Echo Reply。
- MPLS Echo Request/MPLS Echo Reply UDP 的源目端口号为 3503
- MPLS Echo Request 的目的 IP 地址为
127.0.0.1 - MPLS Echo Request 内层 IP TTL 为 1，MPLS TTL 正常
- MPLS Echo Request 中携带 FEC 相关信息。
MPLS Echo Request #
MPLS Echo Reply #
MPLS Echo Request 在 XR 设备中的处理 #
源设备 #
在 MPLS Echo Request send 的源设备上， 数据包会有 RP 的 UDP -> RP SPP -> RP NETIO -> LC SPP -> LC NetIO -> 出接口送出。
从 LC LPTS 中，我们可以检查出从 RP 产生的数据包 counter：
RP/0/RSP0/CPU0:ASR9901-1# show lpts pifib hardware static-police location 0/0/CPU0 | in PUNT_NETIO
Fri Sep 1 05:50:28.611 UTC
PUNT_NETIO_RP_TO_LC_CPU NETIO_HI 5000 1000 12119 0 Local
目的设备 #
RP/0/RSP0/CPU0:ASR9901-2#show packet-trace results
Sun Sep 3 03:02:50.970 UTC
T: D - Drop counter; P - Pass counter
Location | Source | Counter | T | Last-Attribute | Count
------------ ------------ ------------------------- - ---------------------------------------- ---------------
0/0/CPU0 NP0 PACKET_MARKED P TenGigE0_0_0_12 100
0/0/CPU0 NP0 PACKET_FROM_INJECT P 100
0/0/CPU0 NP0 PACKET_TO_PUNT P 300
0/0/CPU0 NP0 PACKET_INGR_TOP_LOOPBACK P 100
0/0/CPU0 NP0 PACKET_INGR_TM_LOOPBACK P 100
0/0/CPU0 SPP-PI CLIENT_PUNT_SUCCESS P stage1 100
0/0/CPU0 NETIO-PI PUNT_DROP D packet_input 100
0/0/CPU0 NETIO-PI BYPASS_IN_COUNT P netio_send_pulse_punt 100
0/0/CPU0 spp-LIB ENTRY_COUNT P SPP PD Punt: stage1 200
0/0/CPU0 netio-LIB ENTRY_COUNT P lpts_pifib_remote_delivers 400
0/0/CPU0 spp-LIB EXIT_COUNT P SPP PD Inject: injectfun 100
0/0/CPU0 netio-LIB EXIT_COUNT P NETIO PD Inject: transmit_pak 100
0/RSP0/CPU0 SPP-PI CLIENT_PUNT_SUCCESS P stage1 100
0/RSP0/CPU0 NETIO-PI BYPASS_MUT_QFULL_DROP D packet_input_bypass 100
0/RSP0/CPU0 NETIO-PI IP_COUNT P netio_send_pulse_input 100
0/RSP0/CPU0 spp-LIB ENTRY_COUNT P SPP PD Punt: stage1 100
0/RSP0/CPU0 netio-LIB ENTRY_COUNT P lpts_npmb_ipv4_delivers 300
0/RSP0/CPU0 udp-LIB ENTRY_COUNT P sosend xipc pulse 100
0/RSP0/CPU0 UDP RECV_NETIO_MANY_RRCVD P udp deliver many-rx 100
0/RSP0/CPU0 UDP RECV_RQUEUED P udp deliver - xipcwrite 100
用 Packet-trace,我们可以很看出这种特殊类型的数据包会经由 NP->LPTS Punt-> LC NetIO -> LC SPP - RP NetIO -> RP SPP.
LPTS Punt 的原因为 PUNT_TTL_EXCEEDED (因为内层的 IP 报文 TTL 为 1):
RP/0/RSP0/CPU0:ASR9901-2#show lpts pifib hardware static-police location 0/0/CPU0
Sun Sep 3 04:13:30.780 UTC
PUNT_TTL_EXCEEDED NETIO_LOW 2000 400 11600 0 Local
因为最终会被送到 RP 的 UDP 上去， 所以我们还有些命令来检查下 UDP 上的一些 counter。
RP/0/RSP0/CPU0:ASR9901-2#show udp brief | in 3503
Sun Sep 3 04:17:59.115 UTC
0x7ff1a401cbd0 0x60000000 0 0 :::3503 :::0
0x7ff1a401a680 0x60000000 0 0 0.0.0.0:3503 0.0.0.0:0
RP/0/RSP0/CPU0:ASR9901-2#
RP/0/RSP0/CPU0:ASR9901-2#
RP/0/RSP0/CPU0:ASR9901-2#show udp statistics pcb 0x7ff1a401a680
Sun Sep 3 04:18:03.382 UTC
Statistics for PCB 0x7ff1a401a680, vrfid 0x60000000
Send: 0 packets received from application
0 xipc pulse received from application
0 packets sent to network (v4/v6 IO)
0 packets sent to network (NetIO)
0 packets failed getting queued to network (v4/v6 IO)
0 packets failed getting queued to network (NetIO)
Rcvd: 11600 packets received from network
11600 packets queued to application (PCB)
0 packets failed queued to application (PCB)
0 packets dropped due to minttl check (PCB)
11600 packets queued to application socket (GLOBAL)
0 packets failed queued to application socket (GLOBAL)
UDP trace 也会保存一些报文的交互， 但是此 buffer 非常的小，保留的信息很快就会被冲掉。
RP/0/RSP0/CPU0:ASR9901-2#show udp trace reverse location 0/rSP0/CPU0 | in 35$
Sun Sep 3 04:18:51.991 UTC
Sep 3 04:18:50.320 udp/event 0/RSP0/CPU0 t8236 udp_input:pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 deliverycnt=1 error 0xb
Sep 3 04:18:50.320 udp/event 0/RSP0/CPU0 t8236 UDP: queue pcb (0x7ff1a401a680) pak (0x63c028ab) to xipc recv q: 3503 -> 3503
Sep 3 04:18:50.320 udp/event 0/RSP0/CPU0 t8236 UDP input: pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 ismulticast=0
Sep 3 04:18:50.315 udp/event 0/RSP0/CPU0 t8236 udp_input:pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 deliverycnt=1 error 0xb
Sep 3 04:18:50.315 udp/event 0/RSP0/CPU0 t8236 UDP: queue pcb (0x7ff1a401a680) pak (0x63c028ab) to xipc recv q: 3503 -> 3503
Sep 3 04:18:50.315 udp/event 0/RSP0/CPU0 t8236 UDP input: pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 ismulticast=0
Sep 3 04:18:50.309 udp/event 0/RSP0/CPU0 t8236 udp_input:pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 deliverycnt=1 error 0xb
Sep 3 04:18:50.309 udp/event 0/RSP0/CPU0 t8236 UDP: queue pcb (0x7ff1a401a680) pak (0x63c028ab) to xipc recv q: 3503 -> 3503
Sep 3 04:18:50.309 udp/event 0/RSP0/CPU0 t8236 UDP input: pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 ismulticast=0
Sep 3 04:18:50.303 udp/event 0/RSP0/CPU0 t8236 udp_input:pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 deliverycnt=1 error 0xb
Sep 3 04:18:50.303 udp/event 0/RSP0/CPU0 t8236 UDP: queue pcb (0x7ff1a401a680) pak (0x63c028ab) to xipc recv q: 3503 -> 3503
Sep 3 04:18:50.303 udp/event 0/RSP0/CPU0 t8236 UDP input: pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 ismulticast=0
Sep 3 04:18:50.296 udp/event 0/RSP0/CPU0 t8236 udp_input:pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 deliverycnt=1 error 0xb
Sep 3 04:18:50.296 udp/event 0/RSP0/CPU0 t8236 UDP: queue pcb (0x7ff1a401a680) pak (0x63c028ab) to xipc recv q: 3503 -> 3503
Sep 3 04:18:50.296 udp/event 0/RSP0/CPU0 t8236 UDP input: pak(0x63c0696b): 3503 -> 3503, vrf 0x60000000, len=64 ismulticast=0
MPLS Echo Reply 在 XR 设备中的处理 #
MPLS Echo Reply 由设备的 RP 产生，送到出向板卡，经正常数据包封装转发出来。
在目的设备中解封装，同样会有 LC Punt 到 RP 上去处理:
RP/0/RSP0/CPU0:ASR9901-1#show packet-trace results
Fri Sep 1 05:43:35.876 UTC
T: D - Drop counter; P - Pass counter
Location | Source | Counter | T | Last-Attribute | Count
------------ ------------ ------------------------- - ---------------------------------------- ---------------
0/0/CPU0 NP0 PACKET_MARKED P TenGigE0_0_0_12 5
0/0/CPU0 NP0 PACKET_TO_PUNT P 5
0/RSP0/CPU0 SPP-PI CLIENT_PUNT_SUCCESS P stage1 5
0/RSP0/CPU0 NETIO-PI BYPASS_MUT_QFULL_DROP D packet_input_bypass 5
0/RSP0/CPU0 NETIO-PI IP_COUNT P netio_send_pulse_input 5
0/RSP0/CPU0 spp-LIB ENTRY_COUNT P SPP PD Punt: stage1 5
0/RSP0/CPU0 netio-LIB ENTRY_COUNT P lpts_npmb_ipv4_delivers 15
0/RSP0/CPU0 udp-LIB ENTRY_COUNT P ip lib - input from netio 10
0/RSP0/CPU0 UDP RECV_NETIO_MANY_RRCVD P udp deliver many-rx 5
0/RSP0/CPU0 UDP RECV_RQUEUED P udp deliver - xipcwrite 5